Prunus spinosa - Blackthorn

Prunus spinosa
Prunus spinosa in Europe: distribution, habitat, usage and threats
I. Popescu, G. Caudullo
The blackthorn (Prunus spinosa L.) is a spiny, deciduous shrub which produces small, purple, edible plums. This species
occurs mostly from south-central Europe up to southern Scandinavia, and eastwards to Asia Minor, growing in forest
margins and open woodlands as part of Mediterranean thermophilous plant communities. It is cultivated as an ornamental
plant and for fruit production, used to make jams, wine, vinegar and distillates. The blackthorn has no important threats,
but it can be a natural host and potential reservoir of diseases affecting production of economically important fruits,
such as apricots, plums, peaches and apples.
The blackthorn, or sloe, (Prunus spinosa L.) is a spiny,
deciduous shrub, growing 1-5 m tall. It forms a dense canopy with
intricate branches and numerous suckers1-4 . Secondary twigs
often transformed into a spine, initially velvety soft, reddishbrown. The buds are globular oval, reddish-brown, more or less
hairy. The bark is dark grey to blackish, slightly grooved. The
leaves are alternate, 2-5 × 1-2 cm long, obovate to oblanceolate,
or elliptical, with margins finely toothed, dull green in colour and
hairless above, usually hairy on the veins underneath1, 3 . The
petioles are 0.2-1 cm long, often hairy. The stipules are elongate,
glandular, toothed, and usually longer than petioles3 . The flowers
are white, 1-1.7 cm wide, usually solitary, appearing before
leaves, numerous, on about 0.5 cm long pedicels1-3 . The sepals
are triangular-ovate, often glandular toothed. Petals have a short
claw (a thinner part at the base of the petal). The stamens are
usually 20, about 0.5 cm long. The anthers are yellow or red3 . The
fruit is 1-1.5 cm drupe, globose, purple covered with a frostlike
bloom, ripening bluish-black, pulp greenish, sour and astringent,
not easily detaching from the endocarp. This species flowers in
March-May. The fruits ripen in late summer and autumn, and are
sometimes persistent on the plant through winter1-3, 5 .
Distribution
This species occurs in most of South-Central Europe, except
the lower half of the Iberian Peninsula, extending northwards to
the southern part of the Scandinavian Peninsula. Eastwards it
reaches Asia Minor, Caucasus and the Caspian Sea. There are
also isolated populations in Tunisia and Algeria1, 6 . It has been
introduced and locally naturalised in North America7 and New
Zealand8 . It grows from lowlands to 1 600 m on Southern Alps
(Switzerland)6, 9 .
Frequency
< 25%
25% - 50%
50% - 75%
> 75%
Chorology
Native
Purple globose drupes covered with a frostlike bloom.
(Copyright Phil Sellens, www.flickr.com: CC-BY)
Map 1: Plot distribution and simplified chorology map for Prunus spinosa.
Frequency of Prunus spinosa occurrences within the field observations as
reported by the National Forest Inventories. The chorology of the native
spatial range for P. spinosa is derived after several sources6, 27-31 .
Habitat and Ecology
The blackthorn occurs in forest margins and openings,
on sunny, rocky slopes, ravines, river valleys, in meadows and
pastures from low elevations to the mountains1, 2, 10 . It is one
of the main species of scrub, a belt of shrubs adjacent to
the forest, in the ecotone between woodland and grassland
communities11, 12 . These Euro-Siberian and Mediterranean
thermophilous communities (class Rhamno-Prunetea) are
dominated by thorny and spiny, scrambling shrubs, developing
in mesic to dry soils at the edges of oak and beech forests or on
river banks with willows and poplars. Rarely are scrubs natural
and permanent, more commonly they are secondary vegetation
developing on disturbed sites or stages of secondary succession in
abandoned meadows or pastures at the borders of the agricultural
landscape. The blackthorn is commonly found with other shrub
species of the genera Rosa, Rubus, Prunus and Cornus, as well
as with spindle tree (Euonymus europaeus), hawthorn (Crataegus
monogyna), wild privet (Ligustrum vulgare), etc.10, 13-16 .
Importance and Usage
As with most Prunus species, the blackthorn has a high
level of hybridisation and crossed with European plum (Prunus
domestica) it forms the hybrid Prunus x fruticans. This species
is considered one of the progenitors of the cultigen European
plum together with cherry plum (Prunus cerasifera)17. Fully ripe
fruits even though astringent are edible, and mainly used to
make jams, jellies, preserves, wine, vinegar, and distilled alcoholic
beverages, or as ingredients of various pastries. Flowers and
petals in particular are used medicinally as tea, syrup, fresh juice
or tincture to fight diarrhoea, anaemia, and other ailments3, 5 . Due
to their vitamin C and the phenolic acids content, the fruits can
be a valuable source of natural antioxidants18 . The blackthorn is
used as an ornamental tree, often as hedges3, 9, 10, 13 . It is also an
important plant for wildlife, its early spring flowers provide nectar
for early pollinators, its branches create a spiny thicket, providing
secure nesting for birds and protection and food for small
mammals13, 19, 20 . In temperate oak forests, its dense and thorny
canopy is difficult to penetrate by large herbivores. Together with
other scrub species, thorny shrubs can protect young palatable
seedlings, such as oak seedlings, against browsing along the
forest edges and clearings21, 22 .
Threats and Diseases
Spiny branches with fruits in autumn.
(Copyright Giovanni Caudullo: CC-BY)
Despite being a member of the Prunus genus, the blackthorn
has no important threats. It can be a natural host and potential
reservoir of diseases affecting production of economically
important fruits, such as apricots, plums, peaches and apples,
and tests have revealed that the presence of wild blackthorns
nearby could be the cause of increased presence of fruit viruses
(e.g. Sharka, dwarf virus, necrotic ring spot virus, chlorotic leaf
spot virus) and fungi (e.g. Taphrina pruni)23-26 .
Hermaphrodite flowers appear in spring and have 5
white petals with 20 stamens.
(Copyright Maja Dumat, www.flickr.com: CC-BY)
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This is an extended summary of the chapter. The full version of
this chapter (revised and peer-reviewed) will be published online at
https://w3id.org/mtv/FISE-Comm/v01/e018f4e. The purpose of this
summary is to provide an accessible dissemination of the related
main topics.
This QR code points to the full online version, where the most
updated content may be freely accessed.
Please, cite as:
Popescu, I., Caudullo, G., 2016. Prunus spinosa in Europe:
distribution, habitat, usage and threats. In: San-Miguel-Ayanz,
J., de Rigo, D., Caudullo, G., Houston Durrant, T., Mauri, A. (Eds.),
European Atlas of Forest Tree Species. Publ. Off. EU, Luxembourg,
pp. e018f4e+
Tree species | European Atlas of Forest Tree Species
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